Devil’s Hole Boulder Caves: Where Outlaws, Legends, and Geology Collide

Tucked into the wooded slopes above Oak Creek lies one of Lancaster County’s curious natural features—a labyrinth of fractured diabase boulders known as the Devil’s Hole Boulder Caves. Generations of locals have referred to the site as “Devil’s Den,” and for more than a century, it has straddled the line between geological wonder and outlaw folklore. Before you even reach the rocks, the setting primes your imagination: a steep hillside, towering trees, and a boulder field so jumbled and imposing that it looks as if it tumbled down the mountain only yesterday.

Local lore says the Devil’s Hole Boulder Caves once offered shelter to all manner of fugitives: draft dodgers, bounty jumpers, horse thieves, moonshiners, and perhaps even murderers. In the 1940 history of Brecknock Township edited by Charles Waters, the caves were described as a favored Sunday hiking destination among Bowmansville’s youth, who shared dramatic stories about the “criminal element” supposedly hiding beneath the slabs.

According to these tales, the boulders conceal walk-in rooms with multiple secret entrances. Intruders pushing into the narrow openings headfirst could be easily ambushed by those inside, while hidden side passages allowed fugitives to slip away. Whether any of this ever truly happened is difficult to verify, yet the caves remain exactly the kind of place where stories cling like moss. Standing at the mouths of the openings today, dark and narrow as they plunge into the hill, it’s easy to understand why the legends persist.

Adding to the mystique are the magnetic anomalies first noted decades ago. Compasses brought to the hillside have been known to swing 10 to 12 degrees off true, influenced by ferruginous minerals within the diabase. A place that confuses both fugitives and compasses needs no help earning an ominous name.

The caves owe their existence to an immense sheet of Triassic diabase, an igneous rock composed mainly of feldspar and augite, that intruded into the surrounding stone more than 200 million years ago. As the diabase slowly cooled, it fractured into massive blocks. Over countless seasons, temperature fluctuations and the hydration of minerals caused the boulders to exfoliate in rounded layers, much like the peeling of an onion.

This gradual reshaping loosened the original rock masses, allowing them to shift and settle into new configurations. Water from the hillside then worked its way between the slabs, eroding debris and enlarging the openings. Post-Triassic faulting may have jostled the boulders farther still, opening crawlways, chambers, and stream passages.

The result is the most extensive known diabase boulder cave system in Lancaster County and possibly in all of Pennsylvania. Despite looking like nothing more than a talus slope to the untrained eye, the interior hides over 200 feet of passages divided among three principal caves.

The Boulder Caves

Boulder Cave No. 1 sits on the northwest edge of the slope. A painted inscription once marked its entrance as “The Den.” This short cave contains roughly 36 feet of passage, threaded by a small independent stream that eventually merges with the larger waters below.

Boulder Cave No. 2, the crown jewel of the system, lies about 130 feet southeast of Cave No. 1. Reaching the main entrance requires ducking beneath a massive diabase slab and dropping eight feet into the darkness. From there, explorers crawl to a keyhole passage that leads into a low chamber where the stream appears. The cave extends approximately 50 feet in both upstream and downstream directions for a total known length of 160 feet. The ceilings range from 2 to 6 feet high, with 8 to 10 feet of boulders overhead.

Boulder Cave No. 3 is located near the base of the boulder slope. It connects to the same stream as Cave No. 2, though the two systems never physically join. Tight openings allow about 40 feet of exploration before the passage pinches down to impossible dimensions.

A recent caver who documented the system on YouTube recounted a harrowing but ultimately successful adventure. After signing a waiver at the campground, he and a friend spent hours scrambling over the boulders, ducking into cramped fissures, discovering neon-colored fungus, surprising crawfish in underground pools, and wriggling through slots that barely accommodated a human ribcage. In the largest cave, he followed the sound of trickling water deep into the passages only to realize he was hopelessly turned around.

With limited light and no cell service, he wandered back and forth until a patch of blue sky appeared through a crevice. He clawed his way out, circled back to the main entrance, re-entered the cave, retrieved his lost pack, and emerged again—rattled but triumphant. It is not difficult to imagine how a 19th-century draft dodger might have vanished among these same stones.

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Note Well

The Devil’s Hole Boulder Caves are a true cave environment: dark, wet, and highly disorienting. Passages involve crawling, squeezing, and navigating slick surfaces near flowing water. Even experienced cavers can become lost. Never enter without permission, proper lighting, a backup light source, a helmet, and a partner. Claustrophobia, low ceilings, and water hazards pose real risks. Respect private property and stay within permitted areas.

Planning Your Visit

The Devil’s Hole Boulder Caves sit on private land owned by Adventure Bound Camping Resorts – Oak Creek. Access is permitted only by checking in at the campground office, signing a waiver, and using the designated trail. Wear sturdy footwear, bring multiple lights, and remember that cave exploration is physically demanding.

From the campground’s southern edge, cross Oak Creek and follow the ascending southwest trail approximately 1,300 feet to the boulder field. The cave’s approximate GPS location is 40.196639, -75.991694.

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Learn More

📖 Learn about other unique places like this when you step off the beaten path with Uncharted Lancaster: Field Guide to the Strange, Storied, and Hidden Places of Lancaster County, Pennsylvania by Adam Zurn. This one-of-a-kind 239-page guidebook uncovers 56 fascinating sites, from the county’s very own fountain of youth to the oldest continuously operating short-line railroad in the western hemisphere.

Packed with history, local stories, and GPS locations, this book is your ticket to exploring the mysterious corners of Lancaster like never before. Whether you’re a lifelong local, a history buff, or just looking for a unique adventure, this field guide will spark your curiosity and send you exploring. Start your adventure here.

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Resources

• Caves of Southeastern Pennsylvania, 1974
• Review of Oak Creek Campground, Narvon, PA
• I got lost in an underground cave network that has never been filmed
• Adventure Bound Camping Resorts – Oak Creek